help. i'm new to using co2 to fix flats on the road. how much pressure do the 16g cartridges supply in a 700x23c tube/tire? if much more than the preferred 100 lbs, how does one gauge the amount of pressure when applying the co2? just a mere thumb test? once arriving back in civilization, is it necessary to remove all the co2 before refilling with pump air? have any other co2 tips you'd like to share? thanks.